Why blood oranges turn red

Every winter someone asks why the Blood orange juice is darker than it was a month ago. The answer is the weather.

Cold nights, warm days

Blood oranges make red pigments called anthocyanins, the same family that colours cherries and red cabbage. The trees only make them when nights turn cold while days stay mild. On the slopes of Etna, where frosty nights follow sunny days, conditions are close to perfect.

Darker as the season goes on

Early in the season the flesh is streaked with red and the juice is ruby. After a few weeks of cold nights it can be almost purple. The taste changes too: from tart and bright to deeper and berry-like.

Why we don't press them all year

By late spring the colour fades and the fruit softens, so we stop. Blood orange is back in December, as soon as the first cold nights have done their work.